Heat storage and transfer system

ABSTRACT

A heat storage and transfer apparatus includes a storage tank, a condenser coil, a solar heat collector, and an evaporator coil. A pump circulates a heat transfer liquid between the condenser coil and the solar heat collector. The solar heat collector raises the temperature of the heat transfer liquid. The condenser coil within the storage tank conducts heat from the transfer liquid and the heat is then absorbed by the thermal media inside the storage tank. Water passes through the evaporator coil and conducts heat from the thermal media, thereby heating the water.

RELATED APPLICATION

The present invention claims priority to U.S. Provisional Patent Application No. 61/086,250, entitled “HEAT STORAGE AND TRANSFER SYSTEM”, filed Aug. 5, 2008, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to systems for the collection, storage and transfer of heat energy and, more particularly, to solar heating systems.

2. Description of the Related Art

There are several inventions relating to the storage and transfer of heat, including the following:

-   U.S. Pat. No. 4,291,756 A heat accumulator comprises a     thermally-insulated reservoir full of paraffin wax mixture or other     flowable or meltable heat-storage mass, heat-exchangers immersed in     the mass, a heat-trap connected to one of the heat-exchangers, and a     heat user connected to the other heat-exchanger. Pumps circulate     fluids through the heat-trap and the heat-using means and the     respective heat-exchangers, and a stirrer agitates and circulates     the mass, and the pumps and the stirrer and electric motors driving     these devices are all immersed in the mass. -   U.S. Pat. No. 4,474,171 A thermal energy storage and transfer system     comprises a water-filled network that includes an interconnected     storage vessel, heat absorber and radiator means. In accordance with     the invention, a hermetically sealed container that has been charged     with a thermal energy storage salt is stationarily submerged in the     water storage vessel. An adjustable louver device is disposed     between the heat absorber and incident solar radiations, and the     louvers or vanes are selectively and automatically opened and closed     in response to the thermal levels in the water storage tank and in     response to the presence or absence of sunlight. -   U.S. Pat. No. 4,574,779 An active solar hot water system includes a     solar collection unit, a heat exchanger, and a draindown tank,     ordered respectively in vertically descending relation. A pump for     drawing thermally conductive recirculation fluid from the draindown     tank and delivering same to the collection unit is positioned     horizontally adjacent the draindown tank for positive gravity prime.     The heat exchanger is disposed either within or is coiled exteriorly     about the lower portion of a water storage tank, for conducting heat     to potable water within the storage tank. Upon system shutdown, the     thermally conductive fluid drains substantially solely into the     draindown tank, providing freeze protection for the collection unit     and minimizing heat drain off from the water storage tank through     the heat exchanger.

SUMMARY OF THE INVENTION

The present invention is directed to a heat storage and transfer apparatus that collects and stores heat energy from an irregular source in order to subsequently provide a constant supply of heat on demand. The apparatus includes an insulated tank filled with a thermal media capable of storing and discharging heat. Heat is introduced to the tank by a hot heat transfer liquid that flows through a condenser coil located centrally within the tank. Heat is removed from the tank by the flow of a cool heat transfer medium through an evaporator coil that traverses the circumference of the tank and has a coil diameter slightly smaller than that of the tank.

The solar storage tank of the invention my capture medium to high temperature heat. The center core may be where the heat is introduced from the solar collector. This center core, which may be referred to herein as the “condenser coil”, may be made of thin copper, so that heat transfers efficiently.

The storage tank may have an outer coil around the outside of the interior of the tank, surrounding the central condenser coil. This outer coil may be referred to herein as the “evaporator coil”. The evaporator coil may draw heat out of the storage tank. The evaporator coil may also be made of thin copper so that heat can transfer efficiently. The condenser coil may have a heat sink type medium so that heat may be transferred quickly. The wall of the tank may be metal, and the outside skin may be made of a high R-value insulation.

A heat-transfer medium between the condenser coil and the evaporator coil may be a granular solid material (like coarse sand). Thus, the medium may be heated to a high temperature without the medium changing state from a liquid to a vapor. This medium may possibly change from a solid to a liquid, however. If this is the case, then latent heat could be stored.

The tank may be used to store heat from solar collectors, or may be used as a heat recovery unit to heat a conditioned space. The tank may be used to store solar heat, enabling use of the heat at night, on cloudy days, or with solar air conditioning.

In one embodiment, the invention comprises a heat storage and transfer apparatus including a storage tank filled with a thermal medium. A condenser coil is centrally disposed within said storage tank and has an inlet and an outlet. A solar energy collection unit is located outside said storage tank and has an inlet and an outlet. A heat transfer liquid flows from said condenser coil to said solar energy collection unit. A first conduit connects said outlet of said solar energy collection unit and the inlet of said condenser coil. A second conduit connects said inlet of said solar energy collection unit and the outlet of said condenser coil. A pump in said second conduit circulates liquid in a circuit between said first conduit, said second conduit, said solar energy collection unit, and said condenser coil. An evaporator coil is disposed within said storage tank, surrounds said condenser coil, and has an inlet and an outlet. In a particular embodiment, the storage tank is filled with paraffin wax as the thermal medium. It is possible that the heat transfer liquid is propylene glycol.

An advantage of the invention is that by the evaporator coil surrounding the condenser coil, the heat from the condenser coil cannot easily escape the tank (e.g., through ambient air, pipes attached to the tank, or the floor) without being first captured by the evaporator coil.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of the invention will become more apparent to one with skill in the art upon examination of the following figures and detailed description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.

FIG. 1 is a cut-away view of one embodiment of the present invention that reveals the inside of the storage tank.

FIG. 2 is an overhead cross-sectional view of the storage tank.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown one embodiment of the heat storage and transfer apparatus 15 of the present invention. Apparatus 15 includes a heat storage tank 45. Tank 45 is filled with thermal storage media 65 and is lined by insulation material 80. A potable cold water input line 70 and a potable hot water output line 50 traverse both the insulation 80 and outside skin 75 of tank 45. Conduits 50, 70 may be disposed in an outer wall of tank 45.

A condenser coil 55 is centrally positioned within tank 45. A feed line 30 is attached to one extremity of coil 55, while a discharge line 40 is attached to the other, both lines traversing the top of tank 45.

An evaporator coil 60 is positioned within tank 45 and surrounds condenser coil 55. Input line 70 and output line 50 are attached to evaporator coil 60 at its extremities.

A solar collection unit 20 is located in an area that will receive a maximum amount of direct sunlight. Collection unit 20 is provided with cool heat transfer liquid through feed line 25 and hot heat transfer liquid is removed from collection unit 20 through feed line 30.

Solar-powered pump 35 provides pressure that circulates the heat transfer liquid between solar collection unit 20 and heat storage tank 45. The heat transfer liquid flows from condenser coil 55 to pump 35 through discharge line 40.

Operation of the system is best illustrated by following the heating cycle. Pump 35 fills collection unit 20 with a heat transfer liquid, preferably a glycol-like substance with a high specific heat capacity. Solar radiation heats collection unit 20, thereby raising the temperature of the heat transfer liquid. Once the heat transfer liquid reaches a predetermined temperature, it is pumped through conduit 30 into condenser coil 55.

The condenser coil 55 is preferably made of copper or some other substance with a high heat transfer capacity and is surrounded by thermal media 65. A heat transfer liquid flows through condenser coil 55 and releases heat energy that is then transferred to and stored within thermal media 65. Insulator 80 prevents the heat energy that has been stored in thermal media 65 from escaping tank 45.

Evaporator coil 60 is used to heat cold water on demand. Evaporator coil 60 is preferably made of copper or some other substance with a high heat transfer capacity and is surrounded by thermal media 65. Cold water is introduced to evaporator coil 60 through input feed 70 using pressure from a standard water system. Cold water passes through evaporator coil 60 and absorbs heat that has been stored in thermal media 65, thereby raising the water's temperature. The water that has been heated by evaporator coil 55 exits tank 45 through output 50 and is then introduced to the existing plumbing system.

FIG. 2 illustrates the spatial relationship between the internal elements of storage tank 45. Thermal media 65 is clearly shown to exist in the areas surrounding both evaporator coil 60 and condenser coil 55. The position of thermal media 65 allows it to collect, store, and discharge heat, depending on the temperature of the fluid being passed through immediately adjacent coils.

While the present invention has been described with reference to specific exemplary embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the invention as set forth in the claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. 

1. A heat storage and transfer apparatus comprising: a substantially hollow, substantially enclosed tank, the tank including first and second fluid inlets and first and second fluid outlets; a first conduit centrally disposed within the tank and being in fluid communication with the first inlet and the first outlet of the tank; a solar energy collection unit disposed outside the tank and being in fluid communication with the first inlet and the first outlet of the tank; a pump in fluid communication with at least one of the first conduit and the solar energy collection unit, the pump being configured to circulate a heat transfer liquid between the first conduit and the solar energy collection unit; a second conduit disposed within the tank and radially outwardly from the first conduit, the second conduit being in fluid communication with the second inlet and the second outlet of the tank; and a thermally conductive heat transfer medium substantially filling the tank and configured to receive heat from the first conduit, store the heat, and transmit the heat to the second conduit.
 2. The apparatus of claim 1 wherein the heat transfer medium comprises paraffin wax.
 3. The apparatus of claim 1 wherein the heat transfer liquid comprises propylene glycol.
 4. The apparatus of claim 1 wherein each of the first conduit and the second conduit is formed of copper.
 5. The apparatus of claim 1 wherein the second inlet comprises a cold water inlet and the second outlet comprises a hot water outlet.
 6. The apparatus of claim 1 wherein the pump is disposed between the first outlet and the solar energy collection unit.
 7. The apparatus of claim 1 wherein the heat transfer medium comprises a granular solid.
 8. A heat storage and transfer apparatus comprising: a substantially hollow, substantially enclosed tank, the tank including first and second fluid inlets and first and second fluid outlets; a first coil centrally disposed within the tank and being in fluid communication with the first inlet and the first outlet of the tank; a solar energy collection unit disposed outside the tank and being in fluid communication with the first inlet and the first outlet of the tank; a pump in fluid communication with at least one of the first coil and the solar energy collection unit, the pump being configured to circulate a heat transfer liquid between the first coil and the solar energy collection unit; a second coil disposed within the tank and substantially surrounding the first coil, the second coil being in fluid communication with the second inlet and the second outlet of the tank; and a thermally conductive heat transfer medium substantially filling the tank and configured to receive heat from the first coil, store the heat, and transmit the heat to the second coil.
 9. The apparatus of claim 8 wherein the heat transfer medium comprises paraffin wax.
 10. The apparatus of claim 8 wherein the heat transfer liquid comprises propylene glycol.
 11. The apparatus of claim 8 wherein each of the first coil and the second coil is formed of copper.
 12. The apparatus of claim 8 wherein the second inlet comprises a cold water inlet and the second outlet comprises a hot water outlet.
 13. The apparatus of claim 8 wherein the pump is disposed between the first outlet and the solar energy collection unit.
 14. A heat storage and transfer apparatus comprising: a substantially hollow, substantially enclosed tank, the tank including: at least one outer wall; first and second fluid inlets; and first and second fluid outlets; a first coil centrally disposed within the tank and being in fluid communication with the first inlet and the first outlet of the tank; a solar energy collection unit disposed outside the tank and being in fluid communication with the first inlet and the first outlet of the tank; a pump in fluid communication with at least one of the first coil and the solar energy collection unit, the pump being configured to circulate a heat transfer liquid between the first coil and the solar energy collection unit; a second coil disposed between the first coil and an outer wall of the tank, the second coil being in fluid communication with the second inlet and the second outlet of the tank; and a thermally conductive heat transfer medium substantially filling the tank and configured to receive heat from the first coil, store the heat, and transmit the heat to the second coil.
 15. The apparatus of claim 14 wherein the heat transfer medium comprises paraffin wax.
 16. The apparatus of claim 14 wherein the heat transfer liquid comprises propylene glycol.
 17. The apparatus of claim 14 wherein each of the first coil and the second coil is formed of copper.
 18. The apparatus of claim 14 wherein the second inlet comprises a cold water inlet and the second outlet comprises a hot water outlet.
 19. The apparatus of claim 14 wherein the pump is disposed between the first outlet and the solar energy collection unit.
 20. The apparatus of claim 14 wherein the heat transfer medium comprises a sand-like material. 